Field of the Invention
The present invention relates to a semiconductor device for use, for example, in a radiofrequency-band wireless apparatus or a radiofrequency-band radar or milliwave-band radar apparatus.
Background Art
There is a demand for reducing in size, improving in performance and reducing in cost in a radiofrequency-band device operating in a radiofrequency band. As a radiofrequency-band device, a monolithic microwave IC (MMIC) having an active element such as a transistor and a matching circuit integrally formed on a semi-insulating substrate is being widely used. The matching circuit is constituted by a passive circuit having, for example, a resistor, a metal-insulator-metal (MIM) capacitor formed of an upper-layer metal, a lower-layer metal and a dielectric film interposed between the upper-layer metal and the lower-layer metal, and a spiral inductor having a wiring metal in looped form.
A chip-scale package (CSP) is ordinarily used as a package for an MMIC. The chip-scale package is a package having solder balls formed on a semiconductor device (MMIC) so that the MMIC can be directly reflow-mounted on a printed circuit board or the like. Japanese Patent Laid-Open No. 2008-066657 discloses a CSP.
Japanese Patent Laid-Open No. 2010-182741 discloses a CSP in which a semiconductor chip is encapsulated in a package of a size substantially equal to the size of the semiconductor chip. Japanese Patent Laid-Open No. 2010-182741 also discloses an arrangement in which a back surface electrode is provided on an upper surface of a semiconductor chip while solder bumps are provided on a lower surface of the semiconductor chip.
A plurality of solder bumps are formed on a front surface of a semiconductor device constituted by a CSP-type MMIC. The plurality of solder bumps are fixed on a substrate to face-down-mount the semiconductor device on the substrate. When the semiconductor device is mounted on the substrate, a back surface portion opposite from the front surface of the semiconductor device is exposed. There is, therefore, a problem that inspection of characteristics of the semiconductor device mounted on the substrate cannot be performed.